This patch requires a non destructive table modification:

sql> ALTER TABLE rr MODIFY COLUMN
 type enum('A','AAAA','ALIAS','CNAME','HINFO','MX','NS','PTR','SRV','TXT');

(Syntax shown is for MySQL database)

It performs server side aliasing for A records.  Aliased records are returned
to the client as normal A records: the client will not know that any
translation took place.  These work anytime an A record is needed, such as
when providing additional records for NS or MX records.

Three errors can occur: the chain can loop, the chain can be broken or the
maximum depth can be exceeded while attempting to complete the chain.  In
the case of any of these errors, the reply is sent without the A record.
Thus, the client will never get nxdomain if an alias exists for the domain,
even if it cannot be completed.

I did a fair amount of testing with this and haven't found any bugs yet.
I haven't yet figured out the CNAME bug, but this should make it less urgent.

--
David Phillips <david@acz.org>
http://david.acz.org/